Processes and systems for using silica particles in fluid bed reactor

ABSTRACT

The present disclosure relates to fluid bed processes that utilize silica particles as a fluidization aid. The process comprises reacting one or more reactants in a reactor comprising a fluid bed to form a product. The fluid bed comprises a catalyst composition comprising a catalyst and an inert additive composition comprising silica particles from 0.5 wt % to 30 wt %, based on the total weight of the catalyst composition. The silica particles are discrete, inert particles that are mixed with the catalyst in the fluid bed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of and the priority to U.S.Provisional Application No. 62/691,225, filed on Jun. 28, 2018, which ishereby incorporated by reference in its entirety for all purposes.

FIELD

The present disclosure relates to fluid bed reactors. More specifically,the present disclosure relates to fluid bed reactors that utilize aninert additive composition comprising silica particles as a fluidizationaid.

BACKGROUND

Some processes for fluidizing a particulate catalyst in a fluid bedreactor are well known. In these processes, a gaseous reactant streamcontacts the catalyst in the fluid bed to convert reactants to desiredreaction products. Typically, some catalyst, e.g., small particlesthereof, becomes entrained in the product stream and must be separatedfrom the product stream after it exits the fluid bed. This is commonlyaccomplished by a particle separation system located downstream of thefluid bed to separate the catalyst from the product stream.Unfortunately, during the fluidization process, a portion of thecatalyst is converted to dust and exits the system with the productstream. Additionally, even with a particle separation system, a portionof the catalyst becomes entrained and lost in the product stream.

In some processes, the fluid bed may include a fluidization aid, e.g.,alumina, to reduce the catalyst loss. The fluidization aid may be mixedwith the catalyst in the fluid bed and the gaseous reactants passthrough and fluidize a bed of catalyst and fluidization aid. Products,byproducts, unreacted reactants, and entrained particulates of catalystand fluidization aid exit the fluid bed and are directed to the particleseparation systems. The particle separation system separates andrecovers a major portion of the particulates while the gaseous productstream passes overhead for further processing, e.g., purification,utilization, or packaging. Conventional fluidization aids used in fluidbed reactors, however, are more dense, harder, and are more roughlyshaped than the catalyst which results in increased erosion of thereactor. When erosion rates are high, there is higher chance ofpremature failure of the reactor leading to high catalyst losses.

For example, U.S. Pat. No. 5,079,379 discloses the use of particulateinert fines, e.g., alumina particles, to reduce solids losses andparticulate catalyst losses in fluidized bed catalytic reactors.

The problem is particularly apparent in ammoxidation processes wherecatalysts of relatively small particle sizes are frequently used. Suchprocesses are disclosed, for example, in U.S. Pat. Nos. 3,164,626;3,335,169; 3,446,834; 3,668,147; and 4,018,712; and 4,590,011; theteachings of which are incorporated herein by reference. U.S. Pat. No.4,590,011 discloses process for the ammoxidation of hydrocarbons tounsaturated nitriles using a fluidized bed containing a mixture ofactive catalyst and discrete particles of an inert material to improvethe yield of nitriles and inhibit the formation of by-products.

Although some references may teach the use of inert particulates influid bed process, the need still exists for improved fluid bedprocesses that reduce catalyst loss and improve product yield withoutcontributing to reactor erosion.

The references identified herein are hereby incorporated by reference.

SUMMARY

In some embodiments, the present disclosure relates to a processcomprising: reacting one or more reactants in a reactor comprising afluid bed to form a product; wherein the fluid bed comprises a catalystcomposition comprising a catalyst and an inert additive compositioncomprising from 0.5 wt % to 30 wt % of silica particles, based on thetotal weight of the catalyst composition, wherein the silica particleshave an equivalent median particle diameter ranging from 10 microns to500 microns. In some aspects, the catalyst comprises one or more ofantimony, uranium, iron, bismuth, vanadium, molybdenum, nickel,potassium, cobalt, oxides thereof, or salts thereof. In some aspects,the catalyst has an equivalent median diameter ranging from 1 microns to125 microns. In some aspects, the silica particles have a real densityranging from 1.8 g/cm³ to 2.8 g/cm³, and wherein the difference betweenthe density of the silica particles and the catalyst is less than 75%.In some aspects, the silica particles have a surface area less than 50m²/g, and wherein the silica particles have a hardness ranging from 500to 720 as measured by ASTM E384 (2018). In some aspects, the silicaparticles have a sphericity ranging from 60% to 99.9%. In some aspects,the catalyst composition further comprises alumina particles, wherein aweight ratio of alumina particles to silica particles is less than 1:1.In some aspects, the inert additive composition comprises no alumina. Insome aspects, the process reduces consumption of the catalyst by greaterthan 5% per kilogram of product produced compared to other fluidizationaids. In some aspects, the silica particles reduce erosion of thereactor by greater than 10% compared to a similar process conductedwithout from 0.5 wt % to 30 wt % silica particles. In some aspects, theprocess demonstrates a product yield greater than 0.2% greater than thatof a similar process conducted without from 0.5 wt % to 30 wt % silicaparticles. In some aspects, the silica particles have a real densityranging from 2.1 g/cm³ to 2.5 g/cm³, wherein the silica particles have asurface area less than 1 m²/g, wherein the silica particles have ahardness ranging from 500 to 720 as measured by ASTM E384 (2018), andwherein the product yield is greater than 70%. In some aspects, thesilica particles have an equivalent median particle diameter rangingfrom 20 microns to 100 microns, wherein the silica particles have a realdensity ranging from 2.1 g/cm³ to 2.5 g/cm³, wherein the silicaparticles have a sphericity greater than 67%, wherein the silicaparticles comprise greater than 99 wt % silica, wherein the productyield is greater than 70%.

In some embodiments, the present disclosure relates to a process forproducing acrylonitrile product, the process comprising: reacting one ormore reactants in a reactor comprising a fluid bed to form anacrylonitrile product; wherein the fluid bed comprises a catalystcomposition comprising a catalyst and an inert additive compositioncomprising silica particles having a density from 1.8 g/cm³ to 2.8g/cm³, wherein the silica particles have a sphericity ranging from 60%to 99.9%. In some aspects, the difference between the density of thesilica particles and the catalyst is less than 75%, wherein the processdemonstrates an acrylonitrile product yield greater than 0.2% greaterthan that of a similar process conducted without silica particles. Insome aspects, the one or more reactants comprises an olefin, ammonia,and an oxygen-containing gas.

In some embodiments, the present disclosure relates to a reactor systemfor preparing acrylonitrile product, comprising: a fluid bed comprisinga catalyst composition comprising a catalyst and an inert additivecomposition comprising from 0.5 wt % to 30 wt % of silica particles,based on the total weight of the catalyst composition; and one or moregas inlet feeds for passing one or more reactants upwardly through thefluid bed to form an acrylonitrile product, wherein the differencebetween the density of the silica particles and the catalyst particlesranges from 0.5% to 75%, wherein the silica particles reduce erosion ofthe reactor by greater than 10% compared to a similar process conductedwithout from 0.5 wt % to 30 wt % silica particles. In some aspects, thesilica particles have a real density ranging from 1.8 g/cm³ to 2.8g/cm³, wherein the silica particles have a surface area less than 50m²/g, wherein the silica particles have a hardness ranging from 500 to720 as measured by ASTM E384 (2018), and wherein the product yield isgreater than 70%. In some aspects, the process demonstrates anacrylonitrile product yield greater than 0.2% greater than that of asimilar process conducted without from 0.5 wt % to 30 wt % silicaparticles. In some aspects, the reactor system further comprises: one ormore gas inlet feeds for passing the one or more reactants upwardlythrough the fluid bed; and one or more cyclones to separate particlesfrom the gas flowing upwardly through the fluid bed of the reactor, thecyclones being in communication with the upwardly flowing gas exitingthe fluid bed, wherein the one or more cyclones comprise a particledischarge pipe for returning separated particles to the fluid bed.

BRIEF DESCRIPTION OF THE DRAWING

The FIGURE shows a schematic diagram of a fluid bed reactor systemincluding cyclones according to embodiments of the present disclosure.

DETAILED DESCRIPTION Introduction

The present disclosure relates to the use of an inert additivecomposition comprising silica particles as a fluidization aid in a fluidbed reactor. The inert additive composition may be mixed with catalystin the fluid bed to improve product yield, reduce catalyst loss, andreduce erosion of the reactor. It has been found that catalystconsumption, e.g., catalyst loss, in a system having a fluid bedreactor, e.g., the cyclone(s) thereof, and optionally a particulateseparation system, e.g., cyclones, downstream of the fluid bed reactor,is significantly reduced when the catalyst is mixed with an inertadditive composition including silica particles.

Conventionally, fluid bed processes have utilized alumina as afluidization aid to improve product yield and inhibit formation ofby-products. However, although the use of alumina may reduce catalystloss compared to processes that do not use a fluidization aid, higherquantities of alumina often reduce the number of reactions per catalystcharge, which adversely affects the overall efficiency of the process.Also, in some instances, alumina has been found to contribute to (amongothers) the problems of reactor erosion, e.g., erosion in the cyclonesystem, which also reduces the efficiency of the process. Generallyspeaking, fluid bed processes that utilize alumina particles have beenshown to consume greater amounts of catalyst without achieving higherproduct yields and selectivity.

It has been found that using silica particles as fluidization aids,e.g., instead of alumina, significantly reduces catalyst loss andreactor erosion in fluid bed processes. In some aspects, the silicaparticles have a specific shape, e.g., spherical, and particle sizedistribution that promotes improved product yields and inhibitsformation of byproducts compared to conventional processes. The specificweight percentage of silica particles in the fluid bed, as well as thedensity and particle shape and/or size of the silica particles,contribute to increased conversion of the reactants and overall yield ofthe process. Without being bound by theory, it is believed that thedensity and/or the specific particle size distribution of the silicaparticles surprisingly retards reactor erosion. In particular, the useof silica particles in fluid bed reactors that have a separation system,e.g., cyclones, downstream from the fluid bed, has been found to haveunexpected erosion reduction benefits.

Alumina particles have high densities as compared to the respectivecatalyst used in the fluid bed. It is postulated that this highdensity/density difference reduces the life of the reactor due toerosion, which leads to catalyst loss. Also, the specific particle sizedistribution of alumina used in fluid bed processes has been found tocontribute to erosion of the reactors thereby reducing the amount ofcatalyst used per charge of the reactor. The inventors have discoveredthat the use of silica particles, e.g., with the specific density andparticle size distribution, surprisingly and unexpectedly contributes toprocess improvements, e.g., product yield, catalyst loss, reactorerosion, and erosion of other units in the process, e.g., separationunits.

Moreover, silica particles used in fluid bed processes are provided in aspecific ratio of catalyst to fluidization aid that beneficiallyprevents loss of catalyst compared to an otherwise identical system thatutilizes another fluidization aid, e.g., alumina particles.

In some cases, the silica particles are inert and discrete particles.The silica particles may be physically mixed with the catalyst in thefluid bed. As used herein, the term “discrete” refers to particlesseparate from and not being a part of the catalyst particle. That is,catalyst support material and deactivated catalyst (unless present asseparate particles) are not considered as constituting any portion ofthe inert additive composition. The term “inert” refers to particlesthat do not significantly catalytically or chemically react with thereactants and/or the products in the fluid bed reactor. In some aspects,the silica particles can be any form of silica provided to the fluid bedreactor as an additive, e.g., fines, particles, compounds, ions, ormixtures thereof. For example, the silica particles may be silica fines.

In some embodiments, the present disclosure is related to processes thatutilize a reactor comprising a fluid bed including a catalystcomposition comprising a catalyst and an inert additive compositioncomprising silica particles. The silica particles may have an equivalentmedian particle diameter ranging from 10 microns to 500 microns. Thesilica particles may be mixed with the catalyst particles in the fluidbed. A feedstock, e.g., reactants, contacts the catalyst composition andinert additive composition in the fluid bed under conditions effectiveto convert greater than a portion of the feedstock to product. Thereactor may, in some embodiments, have one or a plurality of cyclones.

In some embodiments, the present disclosure is related to a process forthe ammoxidation of propylene to acrylonitrile. The process includescharging a feed comprising propylene, ammonia and oxygen to a fluidizedbed operated at ammoxidation conditions. The fluid bed comprising acatalyst composition comprising an active ammoxidation catalyst and aninert additive composition comprising silica particles. The silicaparticles are discrete, inert particles having a particle sizedistribution compatible with fluidization in the fluid bed. The processproduces acrylonitrile which is withdrawn from the fluid bed. Theresulting product, acrylonitrile, is recovered from the reaction zone ofthe fluid bed. The product may be separated to remove catalyst and/orfiltration aid particulates. In some aspects, greater than some of theparticulates are recirculated back to the fluid bed, e.g., from thebottom of the last cyclones of the reactor system to the fluid bed.

Catalyst Composition

The fluid bed comprises a catalyst composition. The catalyst compositionmay vary widely, and generally the catalyst composition can be used tocarry out a variety of chemical reactions, e.g., multiphase reactions.In a fluid bed reactor, a fluid, e.g., gas or liquid, is passed throughthe catalyst composition at sufficient velocities to suspend thecomposition and cause it to behave as though it were a fluid. Thecatalyst composition may comprise a catalyst and an inert additivecomposition. In some embodiments, the catalyst composition comprises thetotal compositional weight of the fluid bed, e.g., the total weight ofthe catalyst and the inert additive composition.

In some embodiments, the inert additive composition does not undulyinterfere with the fluidizing properties of the catalyst compositionused in the fluid bed, and is inert, e.g., imparts no undesirablecatalytic activity and has no undesirable chemical reactivity. In someembodiments, the inert additive composition has little or no catalyticactivity and/or chemical reactivity compared to the catalyst particles.

The catalyst composition comprises an inert additive compositionincluding silica particles. In some embodiments, the inert additivecomposition comprises silica particles ranging from 0.5 wt % to 30 wt %,e.g., from 1 wt % to 28 wt %, from 2 wt % to 26 wt %, from 4 wt % to 24wt %, from 5 wt % to 22 wt %, from 6 wt % to 20 wt %, from 7 wt % to 18wt %, from 8 wt % to 16 wt %, from 9 wt % to 14 wt %, or from 10 wt % to12 wt %, where weight percentages are based on the total weight of thecatalyst composition. In terms of upper limits, the inert additivecomposition may comprise less than 30 wt % of silica particles, e.g.,less than 26 wt %, less than 22 wt %, less than 18 wt %, less than 14 wt%, less than 12 wt %, or less than 11 wt %. In terms of lower limits,the inert additive composition may comprise greater than 0.5 wt % ofsilica particles, e.g., greater than 1 wt %, greater than 2 wt %,greater than 4 wt %, greater than 6 wt %, greater than 8 wt %, orgreater than 10 wt %.

In some embodiments, the inert additive composition comprises from 0.5wt % to 99.99 wt % silica particles, e.g., from 1 wt % to 99.9 wt %,from 5 wt % to 99.5 wt %, from 10 wt % to 99 wt %, from 10 wt % to 98 wt%, from 20 wt % to 95 wt %, from 30 wt % to 90 wt %, from 40 wt % to 85wt %, from 50 wt % to 80 wt %, from 60 wt % to 75 wt %, or from 65 wt %to 70, wherein weight percentages are based on the total weight of theinert additive composition. In terms of lower limits, the inert additivecomposition comprises greater than 0.5 wt % silica particles, e.g.,greater than 1 wt %, greater than 5 wt %, greater than 10 wt %, greaterthan 20 wt %, greater than 30 wt %, greater than 40 wt %, greater than50 wt %, or greater than 60 wt %. In terms of upper limits, the inertadditive composition comprises less than 99.99 wt % silica particles,e.g., less than 99.9 wt %, less than 99.5 wt %, less than 99 wt %, lessthan 95 wt %, less than 90 wt %, less than 85 wt %, less than 80 wt %,or less than 75 wt %. In some embodiments, the inert additivecomposition comprises 99.99 wt % silica particles.

In some embodiments, the silica particles have an equivalent medianparticle diameter ranging from 10 microns to 500 microns, e.g., from 12microns to 400 microns, from 14 microns to 300 microns, from 16 micronsto 200 microns, from 18 microns to 100 microns, from 20 microns to 80microns, from 22 microns to 60 microns, from 24 microns to 50 microns,from 26 microns to 40 microns, or from 28 microns to 36 microns. Interms of upper limits, the silica particles have an equivalent mediandiameter less than 500 microns, e.g., less than 400 microns, less than300 microns, less than 200 microns, less than 150 microns, less than 100microns, or less than 80 microns. In terms of lower limits, the silicaparticles have an equivalent median diameter greater than 10 microns,e.g., greater than 12 microns, greater than 15 microns, greater than 20microns, greater than 25 microns, greater than 30 microns, greater than35 microns, or greater than 40 microns. The equivalent median particlediameter is the diameter of an irregularly-shaped object for a sphere ofan equivalent volume.

The inert additive composition may be combined with the catalyst beforeaddition to the fluid bed. In other cases, the inert additivecomposition and catalyst can be added separately to the fluid bed. Insome aspects, the inert additive composition is mixed in the fluid bedindependent of the catalyst. In some aspects, the inert additivecomposition is provided in the fluid bed before the catalyst is added tofluid bed. In other aspects, the inert additive composition isphysically mixed with the catalyst before being supplied to the fluidbed.

In some aspects, the silica particles, as a whole, may comprise one ormore impurities. As used herein, the term “impurities” refers to atomsor molecules other than silica that are provided with the silicaparticles, e.g., fused with the silica. In some aspects, the silicaparticles may include one or more impurities comprising aluminum, iron,nickel, sodium, boron, calcium, copper, cadmium, magnesium, boron,potassium, phosphorus, and oxides thereof. In some aspects, the silicaparticles comprise one or more of Al₂O₃, Fe₂O₃, Na₂O, K₂O, CaO, and MgO.

In some embodiments, the silica particles comprise SiO₂ ranging from 80wt % to 100 wt %, e.g., from 85 wt % to 99.9 wt %, from 88 wt % to 99.5wt %, from 92 wt % to 99 wt %, from 94 wt % to 98 wt %, or from 95 wt %to 99 wt %, wherein the weight percentage are based on the total weightof the silica particles. In terms of lower limits, the silica particlescomprise greater than 80 wt % SiO₂, e.g., greater than 82 wt %, greaterthan 84 wt %, greater than 88 wt %, greater than 94 wt %, greater than94 wt %, or greater than 96 wt %. In terms of upper limits, the silicaparticles comprise less than 100 wt % SiO₂, e.g., less than 99.9 wt %,less than 99.6 wt %, less than 99.2 wt %, less than 99 wt %, less than98.8 wt %, or less than 98.5 wt %.

In some embodiments, the silica particles comprise impurities rangingfrom 0.01 wt % to 20 wt %, e.g., from 0.05 wt % to 15 wt %, from 0.1 wt% to 10 wt %, from 0.2 wt % to 5 wt %, from 0.4 wt % to 1 wt %, or from0.5 wt % to 0.8 wt %, wherein the weight percentage are based on thetotal weight of the silica particles. In terms of upper limits, thesilica particles comprise less than 20 wt % of impurities, e.g., lessthan 18 wt %, less than 16 wt %, or less than 14 wt %, less than 12 wt%, less than 10 wt %, less than 8 wt %, less than 6 wt %, or less than 4wt %. In terms of lower limits, the silica particles comprise greaterthan 0.01 wt % impurities, e.g., greater than 0.04 wt %, greater than0.08 wt %, greater 0.1 wt %, greater than 0.5 wt %, greater than 1 wt %,greater than 2 wt %, or greater than 3 wt %.

In some embodiments, the silica particles comprise nickel ranging from 1ppm to 150 ppm, e.g., from 10 ppm to 140 ppm, from 20 ppm to 120 ppm,from 30 ppm to 100 ppm, from 40 ppm to 80 ppm, or from 50 ppm to 70 ppm.In terms of upper limits, the silica particles comprise less than 150ppm of nickel, e.g., less than 145 ppm, less than 140 ppm, less than 120ppm, less than 100 ppm, less than 80 ppm, less than 60 ppm, or less than50 ppm. In terms of lower limits, the silica particles comprise greaterthan 1 ppm of nickel, e.g., greater than 5 ppm, greater than 10 ppm,greater than 20 ppm, greater than 25 ppm, greater than 30 ppm, greaterthan 40 ppm, or greater than 45 ppm.

In some embodiments, the silica particles comprise iron ranging from 1ppm to 180 ppm, e.g., from 10 ppm to 160 ppm, from 20 ppm to 140 ppm,from 30 ppm to 120 ppm, from 40 ppm to 100 ppm, or from 60 ppm to 80ppm. In terms of upper limits, the silica particles comprise less than180 ppm of iron, e.g., less than 160 ppm, less than 140 ppm, less than120 ppm, less than 100 ppm, less than 80 ppm, or less than 60 ppm. Interms of lower limits, the silica particles comprise greater than 1 ppmof iron, e.g., greater than 5 ppm, greater than 10 ppm, greater than 20ppm, greater than 25 ppm, greater than 30 ppm, greater than 40 ppm, orgreater than 50 ppm.

The silica particles may have a wide variety of shapes or combination ofdifferent shapes. In some embodiments, silica particles can be sphericalparticles, ellipsoidal particles, cubic particles, rectangularparticles, angular particles, and any combination thereof. According tocertain embodiments, the silica particles are generally sphericalparticles. Further, the silica particles may be selected from hollowparticles and solid particles, and any combination thereof. In someaspects, the silica particles may have no defined shape, e.g.,substantially globular. The inventors have found that the specificparticle size of the silica particles beneficially improves fluidizationof the catalyst composition which increases overall product yield andconversion.

In some embodiments, the silica particles have a sphericity ranging from60% to 99.9%, e.g., from 65% to 99%, from 70% to 95%, from 75% to 90%,from 80% to 90%, from 85% to 95%, or from 90% to 100%. In terms of lowerlimits, the silica particles have a sphericity greater than 60%, e.g.,greater than 65%, greater than 67%, greater than 70%, greater than 75%,greater than 80%, greater than 85%, greater than 88%, greater than 90%,or greater than 90.5%. In terms of upper limits, the silica particleshave a sphericity of less than 99.9%, e.g., less than 99%, less than 98%less than 96%, less than 95%, less than 94%, less than 92%, or less than91%.

In some embodiments, the average particle dimensions of the silicaparticles can have a generally single peaked distribution. For example,all particles could have the same average particle dimension or, asanother example, the particles could have a distribution of averageparticle dimensions, such as a Gaussian distribution, so that theaverage particle dimensions range above and below some mean value.

In some embodiments, the average particle dimension of the silicaparticles may have a multimodal distribution. For example, the averageparticle dimensions may have a bimodal distribution or higher modaldistributions, e.g., trimodal. A multimodal distribution of particledimensions could be useful to, for example, tailor the fluidizationproperties of the catalyst composition. In addition to distributions ofsize, other particle features, such as, for example, particle shape,e.g., angular and spherical silica particles, and particle composition,may be distributed about a single mean or may have a multimodaldistribution.

In some embodiments, the silica particles have a density ranging from1.8 g/cm³ to 2.8 g/cm³, e.g., from 1.9 g/cm³ to 2.7 g/cm³, from 2.0g/cm³ to 2.6 g/cm³, from 2.1 g/cm³ to 2.5 g/cm³, from 2.2 g/cm³ to 2.4g/cm³, or from 2.25 g/cm³ to 2.35 g/cm³. In terms of upper limits, thesilica particles have a density less than 2.8 g/cm³, e.g., less than2.75 g/cm³, less than 2.7 g/cm³, less than 2.6 g/cm³, less than 2.5g/cm³, less than 2.4 g/cm³, or less than 2.3 g/cm³. In terms of lowerlimits, the silica particles have a density greater than 1.8 g/cm³,e.g., greater than 1.9 g/cm³, greater than 1.95 g/cm³, greater than 2.0g/cm³, greater than 2.1 g/cm³, greater than 2.2 g/cm³, or greater than2.25 g/cm³. The inventors have found that the specific density of thesilica particles is similar to the density of the catalyst whichimproves overall fluidization behavior.

In some embodiments, the difference between the density of the silicaparticles and the catalyst particles ranges from 0.5% to 75%, e.g., from1% to 70%, from 2% to 60%, from 4% to 50%, from 6% to 40%, from 8% to30%, or from 10% to 20%. In terms of upper limits, the differencebetween the density of the silica particles and the catalyst particlesis less than 75%, e.g., less than 70%, less than 60%, less than 50%,less than 40%, less than 30%, or less than 25%. In terms of lowerlimits, the difference between the density of the silica particles andthe catalyst particles is greater than 0.5%, e.g., greater than 1%,greater than 2%, greater than 4%, greater than 6%, greater than 8%,greater than 10%, or greater than 15%.

In some embodiments, the silica particles have a surface area rangingfrom 0.01 m²/g to 50 m²/g, e.g., from 0.05 m²/g to 25 m²/g, from 0.08m²/g to 20 m²/g, from 0.1 m²/g to 10 m²/g, from 0.2 m²/g to 5 m²/g, 0.25m²/g to 1 m²/g, or from 0.3 m²/g to 0.6 m²/g. In terms of upper limits,the silica particles have a surface area less than 50 m²/g, e.g., lessthan 25 m²/g, less than 10 m²/g, less than 5 m²/g, or less than 1 m²/g,or less than 0.5 m²/g. In terms of lower limits, the silica particleshave a surface area greater than 0.01 m²/g, e.g., greater than 0.02m²/g, greater than 0.04 m²/g, greater than 0.6 m²/g, greater than 0.08m²/g, greater than 0.1 m²/g, greater than 0.15 m²/g, or greater than 0.2m²/g. The inventors have found that silica particles have a low surfacearea compared to conventional fluidization aids which beneficiallycontributes to increased product yield. Advantageously, the silicaparticles have a lower porosity than conventional fluidization aids,e.g., alumina, which promotes product yield and selectively.

In some embodiments, the silica particles have a hardness ranging from500 to 720 as measured by ASTM E384 (2018), e.g., from 510 to 700, from520 to 680, from 540 to 640, from 550 to 620, from 560 to 600, or from520 to 570. In terms of upper limits, the silica particles have ahardness less than 720, e.g., less than 700, less than 680, less than660, less than 640, less than 620, less than 600, or less than 580. Interms of lower limits, the silica particles have a hardness greater than510, e.g., greater than 515, greater than 520, greater than 525, greaterthan 530, greater than 540, greater than 550, greater than 560, orgreater than 570. The inventors have found that silica particles havehardness values lower than conventional fluidization aids, e.g.,alumina, thereby contributing to less erosion in the reactor.

In some aspects, the catalyst composition may further comprise otherinerts, e.g., alumina. The manner in which the other inerts are providedin the catalyst composition may vary widely. Many techniques are withinthe contemplation of this disclosure and will be suitable, as long asthe other inerts are ultimately present in the fluid bed. As oneexample, other inerts may be deposited in the fluid bed as a residue.For example, alumina particles may be present in the fluid bed fromprevious use of the fluid bed. In other aspects, a small quantity ofother inerts may be added as a component of the inert additivecomposition, e.g., in a manner similar to that of the silica particles.In some aspects, the other inerts present in the fluid bed are entirelysupplied as deposits in the fluid bed, e.g., a residue, and no otherinert particles, e.g., inert additive, is separately added to the fluidbed.

In some embodiments, the inert additive composition comprises otherinerts in an amount ranging from 0.5 wt % to 99.5 wt %, e.g., from 1 wt% to 99 wt %, from 2 wt % to 95 wt %, from 5 wt % to 90 wt %, from 10 wt% to 80 wt %, from 20 wt % to 70 wt %, from 30 wt % to 60 wt %, or from40 wt % to 50 wt %, based on the total weight of the inert additivecomposition. In terms of upper limits, the inert additive compositioncomprises less than 99.5 wt % of other inerts, e.g., less than 99 wt %,less than 90 wt %, less than 80 wt %, less than 70 wt %, less than 60 wt%, less than 50 wt %, less than 40 wt %, or less than 30 wt %. In termsof lower limits, the inert additive composition comprises greater than0.5 wt % of other inerts, e.g., greater than 1 wt %, greater than 2 wt%, greater than 5 wt %, greater than 10 wt %, greater than 12 wt %,greater than 15 wt %, greater than 20 wt %, or greater than 25 wt %. Insome aspects, the catalyst composition and/or inert additive compositiondoes not comprise other inerts, e.g., alumina.

In one embodiment, when other inerts are present in the catalystcomposition, the weight ratio of other inerts to silica particles is inan amount ranging from 0.01:1 to 100:1, e.g., from 0.02:1 to 50:1, from0.04:1 to 25:1, from 0.08:1 to 10:1, from 0.1:1 to 5:1, or from 0.2:1 to1:1, based on the total weight of the catalyst composition. In terms oflower limits, the weight ratio of other inerts to silica particles maybe greater than 0.01:1, e.g., greater than 0.02:1, greater than 0.03:1,greater than 0.04:1, greater than 0.05:1, greater than 0.1:1, greaterthan 0.2:1, or greater than 0.5:1. In terms of upper limits, the weightratio of other inerts to silica particles may be less than 100:1, e.g.,less than 80:1, less than 60:1, less than 40:1, less than 20:1, lessthan 10:1, or less than 1:1.

The catalyst composition may include a wide variety of catalysts thatcan be used to carry out different chemical reactions. The catalystcomposition may comprise catalyst particles supported on a catalystsupport. In some aspects, the catalyst support comprises silica. Thesilica in the catalyst support is separate from the silica particles inthe inert additive composition, e.g., the silica support is not afluidization aid.

In some embodiments, the catalyst comprises one or more of antimony,uranium, iron, bismuth, vanadium, molybdenum, potassium, nickel orcobalt in a catalytically active oxidized state. The catalyst may beindividual oxides or salts of the elements in the selected catalyst. Insome embodiments, the method of preparing the catalyst includescombining oxides, sulfates, or the like of antimony, uranium, iron, andbismuth with sulfuric acid. The catalyst can be shaped to suitableparticle size having a desired surface area. In some aspects, thecatalyst is an active catalyst that is suitable for the ammoxidation ofpropylene to acrylonitrile. The catalyst can be prepared by any knownmethod.

In some embodiments, the fluidized bed in the reaction zone may comprisean active ammoxidation catalyst comprised of one or more of antimony,uranium, and iron along with possibly other metals such as bismuth andmolybdenum. In some aspects, the catalyst is on a support. Inembodiments where a support is used, the catalyst comprises from about 5wt % to about 90 wt %, by weight of the catalyst. Any known supportmaterials can be used, such as, silica, alumina, zirconia, alundum,silicon carbide, aluminasilica, and the inorganic phosphates, silicates,aluminates, borates, and carbonates which are stable under the reactionconditions in the feed reaction zone and do not significantly reduce thecatalytic activity of the active portion of the catalyst.

In some embodiments, the catalyst composition may be specificallyadapted for producing acrylonitrile product. For example, the catalystmixed with the silica particles may be used to convert olefins with orwithout the presence of ammonia to produce acrylonitrile. The olefinsemployed as reactants for the conversion by the catalyst composition maybe open chain, as well as cyclic and include, for example, propylene,butene-1, butene-2, isobutene, pentene-1 pentene-2, 3-methyl butene-1,2-methyl butene-2, hexene-1, hexene-2, 4-methyl pentene-1,3,3-dimethylbutene-1, 4-methyl pentene-2, octene-1, cyclopentene,cyclohexene and the like. In some aspects, mixtures of olefins andmixtures of olefins with other hydrocarbons may be employed in the fluidbed. In some aspects, when the catalyst composition described herein isused for ammoxidation, the olefins mentioned above are applicable. Insome aspects, the fluid bed reactor system is adapted to convert a feedcomprising propylene, ammonia, and oxygen to acrylonitrile.

In some embodiments, the catalyst composition may comprise a catalysthaving an equivalent median diameter ranging from 1 microns to 125microns, e.g., from 2 microns to 120 microns, from 4 microns to 110microns, from 6 microns to 100 microns, from 10 microns to 80 microns,from 20 microns to 70 microns, from 30 microns to 60 microns, from 40microns to 50 microns, or from 45 microns to 55 microns. In someaspects, the catalyst composition includes catalyst having an equivalentmedian diameter less than 125 microns, e.g., less than 120 microns, lessthan 110 microns, less than 100 microns, less than 90 microns, less than80 microns, or less than 70 microns. In some aspects, the catalystcomposition includes catalyst having an equivalent median diametergreater than 1 microns, e.g., greater than 2 microns, greater than 5microns, greater than 10 microns, greater than 15 microns, greater than20 microns, greater than 30 microns, greater than 40 microns, or greaterthan 50 microns.

In some embodiments, the combination of the silica particles and thecatalyst in the fluid bed can synergistically improve product yield andreduce catalyst loss. For example, silica particles having at least oneof the aforementioned properties, e.g., equivalent median particlediameter, density, surface area, hardness, etc., in combination with acatalyst with an equivalent median diameter ranging from 1 microns to125 microns can improve product yield and reduce catalyst loss. Inparticular, using silica particles with a catalyst in a process forproducing acrylonitrile was found to beneficially improve product yieldand reduce catalyst loss. The catalyst can be one or more ofantimony-iron based catalysts, molybdenum-bismuth based catalysts, ironbased catalysts, antimony-iron based catalysts, and oxides thereof.Commercially available catalysts that are suitable include MAC-3 fromMonsanto, Inc.

In some embodiments, the ratio of the equivalent median diameter of thesilica particles to the equivalent median diameter of the catalyst isfrom 0.01:1 to 100:1, e.g., from 0.02:1 to 50:1, from 0.04:1 to 25:1,from 0.08:1 to 10:1, from 0.1:1 to 5:1, or from 0.2:1 to 1:1. In termsof lower limits, the ratio of the equivalent median diameter of thesilica particles to the equivalent median diameter of the catalyst maybe greater than 0.01:1, e.g., greater than 0.02:1, greater than 0.03:1,greater than 0.04:1, greater than 0.05:1, greater than 0.1:1, greaterthan 0.2:1, or greater than 0.5:1. In terms of upper limits, the ratioof the equivalent median diameter of the silica particles to theequivalent median diameter of the catalyst may be less than 100:1, e.g.,less than 80:1, less than 60:1, less than 40:1, less than 20:1, lessthan 10:1, or less than 1:1.

In some aspects, the silica particles have an equivalent median particlediameter ranging from 10 microns to 500 microns, the silica particleshave a surface area less than 50 m²/g, and the product yield is greaterthan 70%.

In some aspects, the silica particles have a real density ranging from2.1 g/cm³ to 2.5 g/cm³, wherein the silica particles have a surface arealess than 50 m²/g, the silica particles have a hardness ranging from 500to 720 as measured by ASTM E384 (2018), and the product yield is greaterthan 70%.

In some aspects, the silica particles have an equivalent median particlediameter ranging from 20 microns to 100 microns, the silica particleshave a real density ranging from 2.1 g/cm³ to 2.5 g/cm³, the silicaparticles have a sphericity greater than 67%, the silica particles havea hardness ranging from 500 to 720 as measured by ASTM E384 (2018), andthe product yield is greater than 70%.

The inventors have found that utilizing silica particles in any fluidbed reactor provides the aforementioned benefits and improvements. Forexample, the process benefits can be seen in ammoxidation processes forproducing nitriles or hydrogen cyanide, selective oxidation processes ofhydrocarbons for producing carboxylic acid, aldehydes, or carboxylicanhydride, oxychlorination processes of hydrocarbon for producing vinylchloride, fluid catalytic cracking (FCC) processes, fluid bed processesfor polyethylene and/or polypropylene, and chemical looping combustionprocesses.

Fluid Bed Reactor System

In some embodiments, the present disclosure relates to reactor systemsfor preparing products, e.g., acrylonitrile. The reactor comprises afluid bed including the catalyst composition and the inert additivecomposition described herein. In some embodiments, the reactor systemmay include one or more gas inlet feeds for passing gases upwardlythrough the fluid bed and one or more cyclones configured to separateparticles from the gas flowing upwardly through the fluid bed of thereactor. The one or more cyclones are in communication with the upwardlyflowing gas exiting the fluid bed.

In some embodiments, the reactor system comprises one or more cyclonesthat separates the catalyst composition and/or the inert additivecomposition entrained in the product stream as it exits the fluid bed.The cyclones separate and recover a major portion of the catalystcomposition while the gaseous product stream passes overhead for furtherpurification, utilization, or packaging. Unfortunately, in conventionalreactor systems, a portion of the catalyst is converted to dust andexits the cyclone with the product stream.

The inventors have found that fluid bed reactor systems including silicaparticles having the aforementioned quantity, size, shape, density,etc., reduce the loss of catalyst compared to in an otherwise identicalsystem not containing silica particles. The reduction in catalyst lossis realized when the fluid bed includes from 0.5 wt % to 30 wt % ofsilica particles, based on the total weight of the catalyst composition.It was found that cyclones had increased efficiency when separating thecatalyst composition from the product stream when utilizing silicaparticles as a fluidization aid. For example, the silica particlescontributed to an increased return of catalyst composition to the fluidbed from the cyclone. Without being bound by theory, it is believed thatthe similar density of the silica particles and the catalyst improvesoverall fluidization behavior, and contributes to an increased return ofcatalyst to the fluid bed. Additionally, it is believed that thespecific particle size and shape of the silica particles reduce erosionin the cyclones compared to conventional fluidization aids.

In some embodiments, the reactor system includes from 1 to 10 cyclones,e.g., from 2 to 8, from 3 to 7, or from 4 to 6. In terms of upperlimits, the reactor system includes less than 10 cyclones, e.g., lessthan 9, less than 8, less than 6, or less than 5. In terms of lowerlimits, the reactor system includes greater than 1 cyclone, e.g.,greater than 2, greater than 3, greater than 4, or greater than 5. Insome aspects, the number of cyclones may be increased until furtherseparation is not possible or is impractical. In some aspects, thecyclones may be arranged in series.

In some embodiments, the cyclones may be located wholly within thereactor. In some aspects, the cyclone is mounted above the fluid bed toreturn the separated catalyst composition to the fluid bed via adischarge pipe. In some embodiments, each of the cyclones may include adischarge pipe to return the separated catalyst composition to the fluidbed. In some aspects, the last cyclone in a series of cyclones comprisesa discharge pipe to return the separated catalyst composition to thefluid bed.

The inventors have also found that use of silica particles, e.g., withthe specific density and particle size distribution, surprisingly andunexpectedly reduces erosion of the reactor system, e.g., the cyclones.In some embodiments, the silica particles reduce erosion of the reactorranging from 10% to 70% compared to a similar process conducted withoutfrom 0.5 wt % to 30 wt % silica particles, e.g., from 15% to 65%, from20% to 60%, from 25% to 55%, from 30% to 50%, or from 35% to 45%. Interms of lower limits, the silica particles reduce erosion of thereactor by greater than 10% compared to a similar process conductedwithout from 0.5 wt % to 30 wt % silica particles, e.g., greater than15%, greater than 20%, greater than 25%, greater than 30%, greater than35%, or greater than 40%.

Additionally, the inventors have also found that the shape of the silicaparticles contribute to reduced erosion in the cyclones. In someembodiments, silica particles having a sphericity ranging from 60% to99.9% have been shown to reduce erosion in the cyclones, e.g., from 65%to 99%, from 70% to 95%, from 75% to 90%, from 80% to 90%, from 85% to95%, or from 90% to 100%. In terms of lower limits, the silica particleshave a sphericity greater than 60%, e.g., greater than 65%, greater than67%, greater than 70%, greater than 75%, greater than 80%, greater than85%, greater than 88%, greater than 90%, or greater than 90.5%. In termsof upper limits, the silica particles have a sphericity of less than99.9%, e.g., less than 99%, less than 98% less than 96%, less than 95%,less than 94%, less than 92%, or less than 91%.

The FIGURE shows a schematic diagram of a fluid bed reactor systemincluding a reactor system according to embodiments of the presentdisclosure. In the fluid bed reactor system 100, a feed of gaseousreactants can enter the system 100 through feed inlets 105, e.g.,spargers, and pass through and fluidize a bed 110 of mixed catalyst andan inert additive composition comprising silica particles. The gaseousreactants can be fed independently to the fluid bed or can be pre-mixedbefore passing through the fluid bed.

The products, byproducts, unreacted reactants, and entrainedparticulates exit through conduit 115 into a first cyclone 120 where amajor portion of the particulates are separated. Exit gas andunseparated particulates flow through top exit 124 into a second cyclone130 for further separation of gas and solids. The separated solidparticulates from the second cyclone 130 are returned to the fluid bed110 via a discharge pipe 132. The remaining exit gas and unseparatedparticulates in the second cyclone 130 flow into a third cyclone 140 forfurther separation. The separated solid particulates from the thirdcyclone 140 are also returned to the fluid bed 110 via a discharge pipe142. The number of cyclones may be increased until further separation isnot possible or is impractical. For purposes of this description, thesolids exiting the top of the last cyclone, e.g., the third cyclone 140,are considered lost or consumed catalyst.

In some embodiments, the feed provided to the fluid bed reactor systemmay comprise an olefin, ammonia, and an oxygen-containing gas. Thecomponents of the feed can be supplied independently to the fluid bed orcan be co-mixed before being supplied to the fluid bed. For example, theolefin and the ammonia can be pre-mixed and supplied to the fluid bed,and the oxygen-containing gas, e.g., air, can be supplied independentlyto the fluid bed. In some embodiments, the molar ratio of oxygen to theolefin in the gas mixture ranges from 0.5:1 to 5:1, e.g., 1:1 to 4:1,from 2:1 to 3:1 or from 2.5:1 to 3.5:1. In terms of lower limits, themolar ratio of oxygen to the olefin in the feed is greater than 0.5:1,e.g., greater than 1:1, greater than 1.5:1, or greater than 2:1. Interms of upper limits, the molar ratio of oxygen to the olefin in thefeed is less than 5:1, e.g., less than 4:1, less than 3:1, or less than2.5:1.

In some embodiments, the molar ratio of ammonia to olefin in the gasmixture ranges from 0.5:1 to 5:1, e.g., 1:1 to 4:1, from 2:1 to 3:1 orfrom 2.5:1 to 3.5:1. In terms of lower limits, the molar ratio ofammonia to the olefin in the feed is greater than 0.5:1, e.g., greaterthan 1:1, greater than 1.5:1, or greater than 2:1. In terms of upperlimits, the molar ratio of ammonia to the olefin in the feed is lessthan 5:1, e.g., less than 4:1, less than 3:1, or less than 2.5:1. Whileammonia is most generally employed as the nitrogen providing compound,other nitrogen containing materials may be employed which chemicallychange to produce reactive nitrogen under the selected reactionconditions. Any source of oxygen, pure or in admixture with inert gases,may be employed in the process. In some embodiments, air can be used asa source of oxygen.

The silica particles in the inert additive composition effectivelyreduces consumption of the catalyst and/or reduces catalyst loss in afluid bed reactor. For example, silica particles reduces consumption ofthe catalyst and/or catalyst loss in the fluid bed reactor compared toother fluidization aids, e.g., alumina. In some embodiments, the silicaparticles reduce consumption of catalyst in range from 5% to 30% perkilogram of product produced, e.g., from 6% to 28%, from 8% to 26%, from10% to 24%, from 12% to 22%, from 14% to 20%, or from 16% to 18%. Interms of lower limits, the silica particles reduce consumption ofcatalyst by greater than 5% per kilogram of product produced, e.g.,greater than 6%, greater than 8%, greater than 10%, greater than 12%,greater than 14%, or greater than 16%. In terms of upper limits, thesilica particles reduce consumption of catalyst by less than 30% perkilogram of product produced, e.g., less than 28%, less than 26%, lessthan 24%, less than 22%, less than 20%, less than 18%. It was found thatfluid bed reactors having silica particles in the fluid bed improves theoverall life of the catalyst.

Beneficially, fluid bed processes that include inert additivecompositions comprising silica also increase overall product yield. Forexample, silica particles improve product yield in fluid bed processescompared to other fluidization aids, e.g., alumina. In some embodiments,the process demonstrates a product yield increase ranging from 0.2% to20% than that of a similar process conducted without from 0.5 wt % to 30wt % silica particles, e.g., a product yield increase ranging from 0.4%to 18%, from 0.6% to 16%, from 0.8% to 14%, from 1% to 12%, from 2% to10%, from 3% to 8%, or from 4% to 7%. In terms of lower limits, theprocess demonstrates a product yield greater than 0.2% greater than thatof a similar process conducted without from 0.5 wt % to 30 wt % silicaparticles, e.g., greater than 0.2%, greater than 0.5%, greater than 1%,greater than 2%, greater than 3%, greater than 4%, greater than 5%,greater than 6%, greater than 7%, greater than 8%, greater than 9%, orgreater than 10%. In terms of upper limits, the process demonstrates aproduct yield less than 20% greater than that of a similar processconducted without from 0.5 wt % to 30 wt % silica particles, e.g., lessthan 19% greater, less than 18% greater, less than 17% greater, lessthan 16% greater, less than 15% greater, less than 14% greater, lessthan 13% greater, less than 12% greater, or less than 11% greater.

Examples

The following examples describe the aspects of the process withreference to its use in an ammoxidation process for producingacrylonitrile. It is understood that the inventive concept is alsoapplicable to other fluid bed systems.

The following examples were done in lab-scale reactors. In the followingexamples, inert additive compositions comprising silica particles wereutilized as a fluidization aid in the fluid bed reactor. The silicaparticles had a particle size distribution as shown in Table 1 asdetermined by Microtrac 53500 (laser light scattering particle sizeanalyzer). The silica particles had a surface area ranging from 0.25m²/g to 0.35 m²/g. The inert additive compositions comprised 99 wt % ofSiO_(2, 2500) ppm of Al₂O₃, 600 ppm of Fe₂O₃, 50 ppm of Na₂O, 100 ppm ofK₂O, 100 ppm of CaO, and 100 ppm of MgO.

TABLE 1 Particle Size D-Values Min (Microns) Max (Microns) 10% 9.1513.13 50% 30.32 40.41 90% 69.44 84.95 *D-value is diameter at which_(——)% of sample's mass is comprised of particles less than the listedvalue.

The inert additive compositions were added to a fluid bed reactorcontaining a catalyst having the formula described in U.S. Pat. No.6,916,763. Adjustments were made to the catalyst and inert additivecompositions in the reactor to obtain a desired propylene conversion andprovide the amounts of each shown in Table 2 below.

Comparative Example 1 utilized no fluidization aid (no alumina orsilica) and Comparative Example 2 utilized 15 wt % of alumina.

A reaction mixture of propylene, air and ammonia was passed through thereactor at fluidization velocities. The exit stream from the reactor wasdivided and passed through separate sets of cyclones. The propyleneconversion, total yield and selectivity of acrylonitrile and otherproducts, coproducts, and byproducts are shown in Table 2. The propyleneconversion, product selectivity and yields, and catalyst activity index(ACT IND) have the same the formula as those described in U.S. Pat. No.6,916,763.

TABLE 2 CO HCN CO₂ ACR ACN Propylene AN AN Catalyst Silica Alumina YieldYield Yield Yield Yield Conv. Sel. Yield Δ ACT Charge Wt % Wt % % % % %% % % % Sel. IND (g) Comp. 1 0 0 4.70 7.58 7.63 0.22 0.35 98.98 79.3178.50 0.67 1.21 380 Comp. 2 0 15 4.84 7.94 7.71 0.10 0.19 98.83 78.9878.06 0.07 1.17 380 Ex. 1 10 0 4.53 6.84 7.46 0.14 0.29 99.08 80.5779.82 2.13 1.23 380 Ex. 2 15 0 4.39 6.63 7.40 0.14 0.31 98.95 80.9480.09 2.25 1.21 376 Ex. 3 20 0 4.36 6.54 7.39 0.14 0.31 99.00 81.0780.26 2.46 1.22 376

It was surprisingly found that the inert additive compositionscomprising silica particles improved acrylonitrile yield and selectivelycompared to fluid bed processes that utilized no fluidization aid orjust alumina as a fluidization aid. For example, each of Examples 1-3utilized from 10 wt % to 20 wt % silica, based on the total weight ofthe catalyst composition, and had greater acrylonitrile yield andselectivity than both Comparative Examples 1 and 2. Beneficially, thesilica particles also reduced the yield of byproducts, e.g., CO, HCN,CO₂, and ACR. Additionally, the examples show the acrylonitrile yieldsand selectivity increased when using silica particles in the fluid bedcompared to a similar process using alumina particles at 15 wt %. Infact, using alumina particles at 15 wt % (Comparative Example 2) reducedacrylonitrile yield compared to a process that used no fluidization aid(Comparative Example 1). The specific weight percentage of silicaparticles in the fluid bed contributed to increased conversion of thereactants and overall yield of the process compared to aluminaparticles.

Table 3 shows propylene conversion, total yield and selectivity ofacrylonitrile using an aged catalyst in a fluid bed process utilizinginert additive compositions comprising silica particles. Comparative 3and Examples 4-6 utilized a used catalyst with different activity andage, e.g., used for certain number of years, than the catalyst used forthe above examples, e.g., fresh catalyst.

TABLE 3 CO HCN CO₂ ACR ACN Propylene AN AN Catalyst Silica Yield YieldYield Yield Yield Conv. Sel. Yield Δ ACT Charge Wt % % % % % % % % %Sel. IND (g) Comp. 3 0 5.19 8.16 7.61 0.24 0.32 99.04 78.28 77.53 −0.230.96 495 Ex. 4 10 4.93 8.08 8.02 0.20 0.19 99.07 78.39 77.66 −0.06 0.95495 Ex. 5 15 4.84 7.98 8.04 0.19 0.19 99.12 78.57 77.88 0.32 0.96 495Ex. 6 20 4.70 7.70 7.96 0.23 0.19 98.86 78.98 78.08 0.12 0.92 495

Generally, the silica particles used with aged catalyst still achievedgood acrylonitrile yield and selectivity. Surprisingly, Examples 4-6show that using silica particles in fluid bed processes improvedacrylonitrile yield even with less active catalyst.

Examples 7-9 and Comparative Examples 4-6 were performed in separateproduction-scale fluid bed reactors. A reaction mixture of propylene,air and ammonia was passed through the reactor at fluidizationvelocities. Inert additive compositions comprising silica particles (5wt. %) were utilized as a fluidization aid in the production-scale fluidbed reactors for Examples 7-9, and no inert additive compositions wereutilized in Comparative Examples 4-6. The acrylonitrile yield for eachcomparative example was normalized to 100 and the acrylonitrile yieldfor each respective example was normalized accordingly. Theacrylonitrile yield increase was calculated from the normalized values.

TABLE 4 Silica Fines Normalized AN AN yield (wt. %) Yield (%) increase(%) Comp. 4 0 100.0 1.20% Example 7 5 101.2 Comp. 5 0 100.0 1.00%Example 8 5 101.0 Comp. 6 0 100.0 0.70% Example 9 5 100.7

In each of Examples 7-9, the total acrylonitrile yield increased by atleast 0.70% compared to the respective Comparative Example. The silicaparticles improved acrylonitrile yield compared to fluid bed processesthat utilized no fluidization aid. For example, each of Examples 7-9demonstrated improved acrylonitrile yield compared to respectiveComparative Examples 4-6.

EMBODIMENTS

The following embodiments are contemplated. All combinations of featuresand embodiments are contemplated.

Embodiment 1: A process comprising: reacting one or more reactants in areactor comprising a fluid bed to form a product; wherein the fluid bedcomprises a catalyst composition comprising a catalyst and an inertadditive composition comprising from 0.5 wt % to 30 wt % of silicaparticles, based on the total weight of the catalyst composition.

Embodiment 2: An embodiment of embodiment 1, wherein the silicaparticles have an equivalent median particle diameter ranging from 10microns to 500 microns.

Embodiment 3: An embodiment of embodiments 1 or 2, wherein the silicaparticles have a real density ranging from 1.8 g/cm³ to 2.8 g/cm³.

Embodiment 4: An embodiment of any of embodiments 1-3, wherein thedifference between the density of the silica particles and the catalystis less than 75%.

Embodiment 5: An embodiment of any of embodiments 1-4, wherein thecatalyst has an equivalent median particle diameter ranging from 1microns to 125 microns.

Embodiment 6: An embodiment of any of embodiments 1-5, wherein thecatalyst composition further comprises alumina particles.

Embodiment 7: An embodiment of any of embodiments 1-6, wherein a weightratio of alumina particles to silica particles is less than 1:1.

Embodiment 8: An embodiment of any of embodiments 1-7, wherein thesilica particles have a surface area less than 50 m²/g.

Embodiment 9: An embodiment of any of embodiments 1-8, wherein thesilica particles have a hardness ranging from 500 to 720 as measured byASTM E384 (2018).

Embodiment 10: An embodiment of any of embodiments 1-9, wherein theinert additive composition comprises no alumina.

Embodiment 11: An embodiment of any of embodiments 1-10, wherein theprocess reduces consumption of the catalyst by greater than 5% perkilogram of product produced compared to other fluidization aids.

Embodiment 12: An embodiment of any of embodiments 1-11, wherein thesilica particles reduce erosion of the reactor by greater than 10%compared to a similar process conducted without from 0.5 wt % to 30 wt %silica particles.

Embodiment 13: An embodiment of any of embodiments 1-12, wherein theprocess demonstrates a product yield greater than 0.2% greater than thatof a similar process conducted without from 0.5 wt % to 30 wt % silicaparticles.

Embodiment 14: An embodiment of any of embodiments 1-13, wherein thesilica particles are mixed with the catalyst in the fluid bed.

Embodiment 15: An embodiment of any of embodiments 1-14, wherein thesilica particles comprise greater than 99 wt % silica.

Embodiment 16: An embodiment of any of embodiments 1-15, wherein thesilica particles comprise impurities ranging from 0.01 wt % to 20 wt %.

Embodiment 17: An embodiment of any of embodiments 1-16, wherein thesilica particles comprise less than 180 ppm of iron and less than 150ppm of nickel.

Embodiment 18: An embodiment of any of embodiments 1-17, wherein thesilica particles have an equivalent median particle diameter rangingfrom 10 microns to 500 microns, wherein the silica particles have asurface area less than 50 m²/g, and wherein the product yield is greaterthan 70%.

Embodiment 19: An embodiment of any of embodiments 1-18, wherein thesilica particles have a real density ranging from 2.1 g/cm³ to 2.5g/cm³, wherein the silica particles have a surface area less than 1m²/g, wherein the silica particles have a hardness ranging from 500 to720 as measured by ASTM E384 (2018), wherein the product yield isgreater than 70%.

Embodiment 20: An embodiment of any of embodiments 1-19, wherein thesilica particles have an equivalent median particle diameter rangingfrom 20 microns to 100 microns, wherein the silica particles have a realdensity ranging from 2.1 g/cm³ to 2.5 g/cm³, wherein the silicaparticles have a sphericity greater than 67%, wherein the silicaparticles comprise greater than 99 wt % silica, wherein the productyield is greater than 70%.

Embodiment 21: An embodiment of any of embodiments 1-20, wherein thecatalyst comprises one or more of molybdenum, bismuth, antimony, iron,uranium, silicon dioxide or mixtures thereof.

Embodiment 22: A process for producing acrylonitrile product, theprocess comprising: reacting one or more reactants in a reactorcomprising a fluid bed to form an acrylonitrile product; wherein thefluid bed comprises a catalyst composition comprising a catalyst and aninert additive composition comprising from 0.5 wt % to 30 wt % of silicaparticles, based on the total weight of the catalyst composition.

Embodiment 23: An embodiment of embodiment 22, wherein the silicaparticles have an equivalent median particle diameter ranging from 10microns to 500 microns.

Embodiment 24: An embodiment of any of embodiments 22 or 23, wherein theprocess demonstrates an acrylonitrile product yield greater than 0.2%greater than that of a similar process conducted without from 0.5 wt %to 30 wt % silica particles.

Embodiment 25: An embodiment of any of embodiments 22-24, wherein theone or more reactants comprises an olefin, ammonia, and anoxygen-containing gas.

Embodiment 26: An embodiment of any of embodiments 22-25, wherein thereactor further comprises: one or more gas inlet feeds for passing theone or more reactants upwardly through the fluid bed; and one or morecyclones configured to separate particles from the gas flowing upwardlythrough the fluid bed of the reactor, the one or more cyclones being incommunication with the upwardly flowing gas exiting the fluid bed.

Embodiment 27: An embodiment of embodiment 26, wherein the one or morecyclones comprise a particle discharge pipe for returning separatedparticles to the fluid bed.

Embodiment 28: A reactor system for preparing acrylonitrile product,comprising: a fluid bed comprising a catalyst composition comprising acatalyst and an inert additive composition comprising from 0.5 wt % to30 wt % of silica particles, based on the total weight of the catalystcomposition; and one or more gas inlet feeds for passing one or morereactants upwardly through the fluid bed to form an acrylonitrileproduct.

Embodiment 29: An embodiment of embodiment 28, wherein the silicaparticles have an equivalent median particle diameter ranging from 10microns to 500 microns.

Embodiment 30: An embodiment of any of embodiments 28 or 29, wherein thesilica particles have a real density ranging from 1.8 g/cm³ to 2.8g/cm³, wherein the silica particles have a surface area less than 50m²/g, and wherein the silica particles have a hardness ranging from 500to 720 as measured by ASTM E384 (2018).

Embodiment 31: An embodiment of any of embodiments 28-30, wherein thesilica particles have a real density ranging from 2.1 g/cm³ to 2.5g/cm³, wherein the silica particles have a surface area less than 1m²/g, wherein the silica particles comprise greater than 99 wt % silica,wherein the product yield is greater than 70%.

Embodiment 32: An embodiment of any of embodiments 28-31, wherein theprocess demonstrates an acrylonitrile product yield greater than 0.2%greater than that of a similar process conducted without from 0.5 wt %to 30 wt % silica particles.

Embodiment 33: An embodiment of any of embodiments 28-32, wherein thesilica particles reduce erosion of the reactor by greater than 10%compared to a similar process conducted without from 0.5 wt % to 30 wt %silica particles.

Embodiment 34: An embodiment of any of embodiments 28-33, wherein thereactor system further comprises: one or more gas inlet feeds forpassing the one or more reactants upwardly through the fluid bed; andone or more cyclones to separate particles from the gas flowing upwardlythrough the fluid bed of the reactor, the cyclones being incommunication with the upwardly flowing gas exiting the fluid bed.

Embodiment 35: An embodiment of embodiment 34, wherein the one or morecyclones comprise a particle discharge pipe for returning separatedparticles to the fluid bed.

Embodiment 36: A process comprising: reacting one or more reactants in areactor comprising a fluid bed to form a product; wherein the fluid bedcomprises a catalyst composition comprising a catalyst and an inertadditive composition comprising from 0.5 wt % to 30 wt % of silicaparticles, based on the total weight of the catalyst composition,wherein the silica particles have an equivalent median particle diameterranging from 10 microns to 500 microns.

Embodiment 37: An embodiment of embodiment 36, wherein the catalystcomprises one or more of antimony, uranium, iron, bismuth, vanadium,molybdenum, nickel, potassium, cobalt, oxides thereof, or salts thereof.

Embodiment 38: An embodiment of embodiment 36, wherein the catalyst hasan equivalent median diameter ranging from 1 microns to 125 microns.

Embodiment 39: An embodiment of embodiment 36, wherein the silicaparticles have a real density ranging from 1.8 g/cm³ to 2.8 g/cm³, andwherein the difference between the density of the silica particles andthe catalyst is less than 75%.

Embodiment 40: An embodiment of embodiment 36, wherein the silicaparticles have a surface area less than 50 m²/g, and wherein the silicaparticles have a hardness ranging from 500 to 720 as measured by ASTME384 (2018).

Embodiment 41: An embodiment of embodiment 36, wherein the silicaparticles have a sphericity ranging from 60% to 99.9%

Embodiment 42: An embodiment of embodiment 36, wherein the catalystcomposition further comprises alumina particles, wherein a weight ratioof alumina particles to silica particles is less than 1:1.

Embodiment 43: An embodiment of embodiment 36, wherein the inertadditive composition comprises no alumina.

Embodiment 44: An embodiment of embodiment 36, wherein the processreduces consumption of the catalyst by greater than 5% per kilogram ofproduct produced compared to other fluidization aids.

Embodiment 45: An embodiment of embodiment 36, wherein the silicaparticles reduce erosion of the reactor by greater than 10% compared toa similar process conducted without from 0.5 wt % to 30 wt % silicaparticles.

Embodiment 46: An embodiment of embodiment 36, wherein the processdemonstrates a product yield greater than 0.2% greater than that of asimilar process conducted without from 0.5 wt % to 30 wt % silicaparticles.

Embodiment 47: An embodiment of embodiment 36, wherein the silicaparticles have a real density ranging from 2.1 g/cm³ to 2.5 g/cm³,wherein the silica particles have a surface area less than 1 m²/g,wherein the silica particles have a hardness ranging from 500 to 720 asmeasured by ASTM E384 (2018), and wherein the product yield is greaterthan 70%.

Embodiment 48: An embodiment of embodiment 36, wherein the silicaparticles have an equivalent median particle diameter ranging from 20microns to 100 microns, wherein the silica particles have a real densityranging from 2.1 g/cm³ to 2.5 g/cm³, wherein the silica particles have asphericity greater than 67%, wherein the silica particles comprisegreater than 99 wt % silica, wherein the product yield is greater than70%.

Embodiment 49: A process for producing acrylonitrile product, theprocess comprising: reacting one or more reactants in a reactorcomprising a fluid bed to form an acrylonitrile product; wherein thefluid bed comprises a catalyst composition comprising a catalyst and aninert additive composition comprising silica particles having a densityfrom 1.8 g/cm³ to 2.8 g/cm³, wherein the silica particles have asphericity ranging from 60% to 99.9%.

Embodiment 50: An embodiment of embodiment 49, wherein the differencebetween the density of the silica particles and the catalyst is lessthan 75%, wherein the process demonstrates an acrylonitrile productyield greater than 0.2% greater than that of a similar process conductedwithout silica particles.

Embodiment 51: An embodiment of embodiment 49, wherein the one or morereactants comprises an olefin, ammonia, and an oxygen-containing gas.

Embodiment 52: A reactor system for preparing acrylonitrile product,comprising: a fluid bed comprising a catalyst composition comprising acatalyst and an inert additive composition comprising from 0.5 wt % to30 wt % of silica particles, based on the total weight of the catalystcomposition; and one or more gas inlet feeds for passing one or morereactants upwardly through the fluid bed to form an acrylonitrileproduct, wherein the difference between the density of the silicaparticles and the catalyst particles ranges from 0.5% to 75%, whereinthe silica particles reduce erosion of the reactor by greater than 10%compared to a similar process conducted without from 0.5 wt % to 30 wt %silica particles.

Embodiment 53: An embodiment of embodiment 52, wherein the silicaparticles have a real density ranging from 1.8 g/cm³ to 2.8 g/cm³,wherein the silica particles have a surface area less than 50 m²/g,wherein the silica particles have a hardness ranging from 500 to 720 asmeasured by ASTM E384 (2018), and wherein the product yield is greaterthan 70%.

Embodiment 54: An embodiment of embodiment 52, wherein the processdemonstrates an acrylonitrile product yield greater than 0.2% greaterthan that of a similar process conducted without from 0.5 wt % to 30 wt% silica particles.

Embodiment 55: An embodiment of embodiment 52, wherein the reactorsystem further comprises: one or more gas inlet feeds for passing theone or more reactants upwardly through the fluid bed; and one or morecyclones to separate particles from the gas flowing upwardly through thefluid bed of the reactor, the cyclones being in communication with theupwardly flowing gas exiting the fluid bed, wherein the one or morecyclones comprise a particle discharge pipe for returning separatedparticles to the fluid bed.

While the invention has been described in detail, modifications withinthe spirit and scope of the invention will be readily apparent to thoseof skill in the art. In view of the foregoing discussion, relevantknowledge in the art and references discussed above in connection withthe Background and Detailed Description, the disclosures of which areall incorporated herein by reference. In addition, it should beunderstood that embodiments of the invention and portions of variousembodiments and various features recited herein and/or in the appendedclaims may be combined or interchanged either in whole or in part. Inthe foregoing descriptions of the various embodiments, those embodimentswhich refer to another embodiment may be appropriately combined withother embodiments as will be appreciated by one of skill in the art.

We claim:
 1. A process comprising: reacting one or more reactants in areactor comprising a fluid bed to form a product; wherein the fluid bedcomprises a catalyst composition comprising a catalyst and an inertadditive composition comprising from 0.5 wt % to 30 wt % of silicaparticles, based on the total weight of the catalyst composition,wherein the silica particles have an equivalent median particle diameterranging from 10 microns to 500 microns.
 2. The process of claim 1,wherein the catalyst comprises one or more of antimony, uranium, iron,bismuth, vanadium, molybdenum, nickel, potassium, cobalt, oxidesthereof, or salts thereof.
 3. The process of claim 1, wherein thecatalyst has an equivalent median diameter ranging from 1 microns to 125microns.
 4. The process of claim 1, wherein the silica particles have areal density ranging from 1.8 g/cm³ to 2.8 g/cm³, and wherein thedifference between the density of the silica particles and the catalystis less than 75%.
 5. The process of claim 1, wherein the silicaparticles have a surface area less than 50 m²/g, and wherein the silicaparticles have a hardness ranging from 500 to 720 as measured by ASTME384 (2018).
 6. The process of claim 1, wherein the silica particleshave a sphericity ranging from 60% to 99.9%
 7. The process of claim 1,wherein the catalyst composition further comprises alumina particles,wherein a weight ratio of alumina particles to silica particles is lessthan 1:1.
 8. The process of claim 1, wherein the inert additivecomposition comprises no alumina.
 9. The process of claim 1, wherein theprocess reduces consumption of the catalyst by greater than 5% perkilogram of product produced compared to other fluidization aids. 10.The process of claim 1, wherein the silica particles reduce erosion ofthe reactor by greater than 10% compared to a similar process conductedwithout from 0.5 wt % to 30 wt % silica particles.
 11. The process ofclaim 1, wherein the process demonstrates a product yield greater than0.2% greater than that of a similar process conducted without from 0.5wt % to 30 wt % silica particles.
 12. The process of claim 1, whereinthe silica particles have a real density ranging from 2.1 g/cm³ to 2.5g/cm³, wherein the silica particles have a surface area less than 1m²/g, wherein the silica particles have a hardness ranging from 500 to720 as measured by ASTM E384 (2018), and wherein the product yield isgreater than 70%.
 13. The process of claim 1, wherein the silicaparticles have an equivalent median particle diameter ranging from 20microns to 100 microns, wherein the silica particles have a real densityranging from 2.1 g/cm³ to 2.5 g/cm³, wherein the silica particles have asphericity greater than 67%, wherein the silica particles comprisegreater than 99 wt % silica, wherein the product yield is greater than70%.
 14. A process for producing acrylonitrile product, the processcomprising: reacting one or more reactants in a reactor comprising afluid bed to form an acrylonitrile product; wherein the fluid bedcomprises a catalyst composition comprising a catalyst and an inertadditive composition comprising silica particles having a density from1.8 g/cm³ to 2.8 g/cm³, wherein the silica particles have a sphericityranging from 60% to 99.9%.
 15. The process of claim 14, wherein thedifference between the density of the silica particles and the catalystis less than 75%, wherein the process demonstrates an acrylonitrileproduct yield greater than 0.2% greater than that of a similar processconducted without silica particles.
 16. The process of claim 14, whereinthe one or more reactants comprises an olefin, ammonia, and anoxygen-containing gas.
 17. A reactor system for preparing acrylonitrileproduct, comprising: a fluid bed comprising a catalyst compositioncomprising a catalyst and an inert additive composition comprising from0.5 wt % to 30 wt % of silica particles, based on the total weight ofthe catalyst composition; and one or more gas inlet feeds for passingone or more reactants upwardly through the fluid bed to form anacrylonitrile product, wherein the difference between the density of thesilica particles and the catalyst particles ranges from 0.5% to 75%,wherein the silica particles reduce erosion of the reactor by greaterthan 10% compared to a similar process conducted without from 0.5 wt %to 30 wt % silica particles.
 18. The system of claim 17, wherein thesilica particles have a real density ranging from 1.8 g/cm³ to 2.8g/cm³, wherein the silica particles have a surface area less than 50m²/g, wherein the silica particles have a hardness ranging from 500 to720 as measured by ASTM E384 (2018), and wherein the product yield isgreater than 70%.
 19. The system of claim 17, wherein the processdemonstrates an acrylonitrile product yield greater than 0.2% greaterthan that of a similar process conducted without from 0.5 wt % to 30 wt% silica particles.
 20. The system of claim 17, wherein the reactorsystem further comprises: one or more gas inlet feeds for passing theone or more reactants upwardly through the fluid bed; and one or morecyclones to separate particles from the gas flowing upwardly through thefluid bed of the reactor, the cyclones being in communication with theupwardly flowing gas exiting the fluid bed, wherein the one or morecyclones comprise a particle discharge pipe for returning separatedparticles to the fluid bed.